1. Field of the Invention
The invention relates to a method for the ultrasonic inspection of pipe and tubing to determine characteristics thereof, such as wall thickness or defects, and to a transducer assembly for use with this method.
2. Description of the Prior Art
Incident to the manufacture or use of tubular products, it is common practice to inspect the tubing for detection of variations in the wall thickness thereof and to detect the presence of surface and internal defects. For this purpose, it is known to use ultrasonic inspection techniques. With these techniques, it is customary to employ a transducer to impart high-frequency sound energy into the tubing to be tested. The high-frequency sound energy is transmitted through an ultrasonic fluid to the tubing and is reflected back from the tubing to the transducer. Monitoring of this back reflection of the sound energy is used to determine characteristics such as wall thickness and the presence of defects in the form of discontinuities in the tubing.
With inspection techniques of this type, relative rotational movement is imparted between the tubing being inspected and the transducer assembly used for the inspection. To achieve precise and reliable test results, it is necessary to maintain effective ultrasonic coupling between the transducers and the surface of the tubing during this relative rotational movement. This necessitates a transducer assembly having a surface coupled to the transducers that conforms to the contour of the surface of the tubing being inspected. To maintain this contact, it is desirable that the contacting surface of the transducer assembly be of a material that will deform into conformity with the tubing contour. For effective ultrasonic coupling, contact of the conforming material must be maintained while effecting relative rotational movement of the tubing surface and the conforming material of the transducer assembly. This results in rapid wear and destruction of this conforming surface of the transducer assembly and thus necessitates frequency removal and replacement. If the surface is attempted to be maintained in light contact to avoid wear and abrasion thereof, this results in ineffective ultrasonic coupling of the transducers and thus imprecise and unreliable test results.